Near‐Infrared Emitting Materials via Harvesting Triplet Excitons: Molecular Design, Properties, and Application in Organic Light Emitting Diodes

Abstract Near‐infrared (NIR) emitting materials have attracted considerable attention because of their potential applications in organic light emitting diodes, bioimaging, military, etc. The research on NIR‐emitting materials and devices is motivated by fundamental and practical application demands. In these developed NIR‐emitting materials, transition metal complexes, and thermally activated delayed fluorescence (TADF) molecules, which can harvest triplet excitons, have exhibited significant potential because their theoretical internal quantum efficiency can reach 100%. Herein, the development of these NIR‐emitting materials of transition metal complexes and TADF molecules is reviewed and, furthermore, a clear outlook for a broad range of applications in many disciplinary areas is provided.